Watts Calculator
Convert between watts, kilowatts, megawatts, and gigawatts. Calculate power consumption, energy usage in kilowatt-hours, and estimate electricity costs. Perfect for understanding appliance power ratings, sizing generators, and managing home energy usage.
📊 Typical Appliance Power Consumption
| Appliance | Typical Wattage (W) | Monthly kWh (8 hrs/day) | Monthly Cost ($0.12/kWh) |
|---|---|---|---|
| LED Light Bulb | 8-12 | 2.9 | $0.35 |
| Laptop | 50-100 | 24 | $2.88 |
| Desktop Computer | 200-400 | 96 | $11.52 |
| TV (55-inch LED) | 80-150 | 36 | $4.32 |
| Refrigerator | 100-250 | 60 | $7.20 |
| Microwave | 800-1500 | 48 | $5.76 |
| Clothes Washer | 400-1200 | 36 | $4.32 |
| Clothes Dryer | 2000-5000 | 120 | $14.40 |
| Dishwasher | 1200-2400 | 36 | $4.32 |
| Air Conditioner (window) | 500-1500 | 360 | $43.20 |
| Space Heater | 1000-1500 | 360 | $43.20 |
| Water Heater | 3000-4500 | 720 | $86.40 |
Understanding Watts, Power, and Energy
Power and energy are related but distinct concepts:
- Power is the rate at which energy is generated or consumed. It is measured in watts (W). One watt equals one joule per second.
- Energy is the total amount of work done or electricity consumed over time. It is measured in watt-hours (Wh) or kilowatt-hours (kWh).
The relationship is: Energy (kWh) = Power (kW) × Time (hours)
Key Conversions:
1 kW = 1,000 W
1 MW = 1,000 kW = 1,000,000 W
1 GW = 1,000 MW = 1,000,000 kW
1 kWh = 1,000 Wh
A watt is the standard unit of power in the International System of Units (SI). It is used to rate the power consumption of appliances, light bulbs, and electronic devices. For example, a 100-watt light bulb uses 100 watts of power when turned on.
How the Watts Calculator Works
This calculator supports two modes:
- Power Converter: Convert between watts (W), kilowatts (kW), megawatts (MW), and gigawatts (GW).
- Energy & Cost: Calculate daily, monthly, and annual energy consumption in kWh and estimate electricity costs based on your local rate.
For the energy & cost mode, the formulas are:
- Daily Energy (kWh) = Power (kW) × Hours Used
- Monthly Energy (kWh) = Daily Energy × Days Used
- Monthly Cost = Monthly Energy × Cost per kWh
For example: A 100-watt appliance used 8 hours per day for 30 days:
0.1 kW × 8 × 30 = 24 kWh per month. At $0.12/kWh, the monthly cost is $2.88.
Why Use This Watts Calculator?
- Comprehensive: Supports power conversions and energy cost calculations.
- Practical: Estimate the cost of running appliances and electronics.
- Educational: See the formula and step-by-step calculation breakdown.
- Visual Comparison: A bar chart shows the relative scale of different units.
- Free & Private: No registration, no data storage.
❓ Watts Calculator FAQ
What is a watt?
A watt (W) is the SI unit of power, equal to one joule per second. It measures the rate at which energy is generated or consumed. For example, a 100-watt light bulb uses 100 joules of energy every second.
How do I convert watts to kilowatts?
Divide watts by 1,000. For example, 1,500 W ÷ 1,000 = 1.5 kW. The formula is: kW = W ÷ 1,000.
How do I convert kilowatts to watts?
Multiply kilowatts by 1,000. For example, 2.5 kW × 1,000 = 2,500 W.
What is a kilowatt-hour (kWh)?
A kilowatt-hour (kWh) is a unit of energy equal to 1,000 watt-hours. It is the standard unit used on electricity bills to measure consumption. One kWh is the energy used by a 1,000-watt appliance running for 1 hour.
How do I calculate energy consumption in kWh?
Energy (kWh) = Power (kW) × Time (hours). For example, a 100 W (0.1 kW) appliance running for 8 hours uses 0.1 × 8 = 0.8 kWh.
How do I calculate the cost of running an appliance?
Cost = Energy (kWh) × Cost per kWh. For example, using 0.8 kWh at $0.12/kWh costs 0.8 × 0.12 = $0.096 per day.
What is the average cost of electricity per kWh?
The average electricity cost in the US is about $0.12-0.16 per kWh, but rates vary by state and utility provider. Use this calculator with your local rate for accurate estimates.
How many watts does a typical refrigerator use?
A typical refrigerator uses 100-250 watts, running about 8-12 hours per day (the compressor cycles on and off). Monthly consumption is roughly 60-80 kWh.
What is the difference between a watt and a kilowatt?
A watt (W) is the base unit of power. A kilowatt (kW) is 1,000 watts. Kilowatts are commonly used for larger appliances and electricity billing.
What is a megawatt (MW)?
A megawatt (MW) is a unit of power equal to 1,000,000 watts or 1,000 kilowatts. It is used to measure the capacity of large power plants and industrial equipment.
How do I calculate the monthly cost of an appliance?
Monthly Cost = (Watts ÷ 1,000) × Hours per Day × Days per Month × Cost per kWh. This calculator does this for you automatically.
What is standby power consumption?
Standby power (also called vampire power) is the electricity consumed by devices when they are turned off but still plugged in. Many electronics draw 1-10 watts in standby mode, which can add up over time.
How many watts does a laptop use?
A typical laptop uses 50-100 watts when charging and running. In sleep mode, it uses 5-15 watts. This calculator can help you estimate the cost of running your laptop.
What is the difference between watts and volt-amps (VA)?
Watts measure real power, while volt-amps (VA) measure apparent power. For purely resistive loads (like incandescent bulbs), watts = VA. For inductive loads (like motors), watts = VA × power factor.
How do I size a generator for my home?
Add up the wattage of all appliances you want to run simultaneously. This calculator can help you convert between watts and kilowatts to determine the required generator capacity.
What is a gigawatt (GW)?
A gigawatt (GW) is a unit of power equal to 1,000 megawatts or 1,000,000 kilowatts. It is used to measure the capacity of large power plants and national power grids.
How do I convert watts to megawatts?
Divide watts by 1,000,000. For example, 5,000,000 W ÷ 1,000,000 = 5 MW.
How can I reduce my electricity bill?
Use energy-efficient appliances, turn off devices when not in use, unplug chargers, use LED bulbs, and adjust thermostat settings. This calculator helps you identify which appliances cost the most to run.